import copy

def copy_test():
    a = [[1,2],[3,4]]
    b = a.copy() # 浅拷贝：修改子元素会相互影响
    c = copy.deepcopy(b) # 深拷贝：修改任何数据都不会影响原对象
    a[0][0] = 100
    print("a = ",a)
    print("b = ",b)
    print("c = ",c)

copy_test()